First, I think this depends a lot on your locality. I think you'll find a lot of places where people are nowhere near as complimentary about basic government services like DMV as you seem to be.

Second, I think this depends a lot on the type of service and how large a segment of the population needs it. Everybody gets driver's licenses, so there is a limit to how much suckitude the DMV can have before it becomes a political issue. But many social services are only used by a small fraction of the population, so unless you are one of those people or know one of them closely enough, you won't be aware of how much those services suck, and if you are aware of it, you will have a very hard time getting other people, who don't use the services and don't know anyone who does, to care. And the people who do need those services are usually those who have little if any ability to push back at suckitude.

Finally, I think you are ignoring the huge difference in how the incentives of a government organization are determined, as compared with those of a corporation. A corporation is a business: its fundamental incentive is to make money. Corporations that don't do that go out of business. A government organization, however, has whatever incentives were put in place by the political process that created it (and those incentives can gradually change as the political process changes); and the one constant about government organizations is that, once they're created, they never go away.